Zvonarev, I. E., S. L. Ivanov, A. S. Fokin, and D. A. Shibanov. “Residual Life Assessment Gears Coarse-Grained Open Transfer of Mining Machines Based on the Local Changes of Their Surface Hardness”. Journal of Mining Institute 209 (1): 31. Accessed September 28, 2020. http://pmi.spmi.ru/index.php/pmi/article/view/5277.